It is, unless you are a donator and you then can choose when you edit something to show the message. I assume you were editing your own post and didn't select that option. I've removed that feature from that group.
Some archived threads were removed a while back and that discussion is on other threads. No thread of value should have been in any archive, but I can't rewind time and manually review every move.
Embed linking is all or nothing option for the site. Since people like YouTube, it'll stay on.